Toroidal bearings are single-row radial roller bearings with barrel-shaped roller bodies that roll on corresponding concave raceways and are guided not by one or two rims, but only by frictional forces. A toroidal bearing is known, e.g., from EP 0 175 858 A1.
Toroidal bearings have a certain radial play of the barrel-shaped roller bodies between the outer ring and the inner ring. This radial play generates a relatively large axial play, so that a toroidal bearing can tolerate an axial displacement between the outer ring and inner ring. A toroidal bearing can thus be used basically in certain applications as loose bearings. Due to the concave raceways and the barrel-shaped roller bodies, a toroidal bearing can also compensate for slightly misaligned positions of the shaft to be supported.
Shaft bearings comprising a self-aligning roller bearing as a fixed bearing point and a self-aligning roller bearing as a loose bearing point (e.g., with radially free outer ring) can be equipped, under some circumstances, with a toroidal bearing as a replacement of the self-aligning roller bearing in the loose bearing point. Here, certain structural adjustments to the surroundings of the loose bearing point are required. Among other things, spacer disks normally must be used, in order to adjust the toroidal bearing in the available installation space. If a relubricating option of the loose bearing point is required, the measures that are typical in single-row radial roller bearings must also be provided: it must be possible to feed lubricant in the axial direction. For this purpose, in part, very complicated structural adjustments of the surrounding construction are necessary. For example, nozzles are typically provided for introducing the lubricant in toroidal bearings or new lubricating channels are formed in the surrounding construction.